[PATCH] x86-64: Use physflat on Intel for < 8 CPUs with CPU hotplug

[pandora-kernel.git] / arch / x86_64 / kernel / genapic.c

diff --git a/arch/x86_64/kernel/genapic.c b/arch/x86_64/kernel/genapic.c
index b1c144f..7a64ea1 100644 (file)
--- a/arch/x86_64/kernel/genapic.c
+++ b/arch/x86_64/kernel/genapic.c
@@ -45,7 +45,7 @@ void __init clustered_apic_check(void)
        u8 clusters, max_cluster;
        u8 id;
        u8 cluster_cnt[NUM_APIC_CLUSTERS];
-       int num_cpus = 0;
+       int max_apic = 0;
 
 #if defined(CONFIG_ACPI)
        /*
@@ -64,14 +64,15 @@ void __init clustered_apic_check(void)
                id = bios_cpu_apicid[i];
                if (id == BAD_APICID)
                        continue;
-               num_cpus++;
+               if (id > max_apic)
+                       max_apic = id;
                cluster_cnt[APIC_CLUSTERID(id)]++;
        }
 
        /* Don't use clustered mode on AMD platforms. */
        if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
                genapic = &apic_physflat;
-#ifndef CONFIG_CPU_HOTPLUG
+#ifndef CONFIG_HOTPLUG_CPU
                /* In the CPU hotplug case we cannot use broadcast mode
                   because that opens a race when a CPU is removed.
                   Stay at physflat mode in this case.
@@ -79,7 +80,7 @@ void __init clustered_apic_check(void)
                   we have ACPI platform support for CPU hotplug
                   we should detect hotplug capablity from ACPI tables and
                   only do this when really needed. -AK */
-               if (num_cpus <= 8)
+               if (max_apic <= 8)
                        genapic = &apic_flat;
 #endif
                goto print;
@@ -103,9 +104,14 @@ void __init clustered_apic_check(void)
         * (We don't use lowest priority delivery + HW APIC IRQ steering, so
         * can ignore the clustered logical case and go straight to physical.)
         */
-       if (clusters <= 1 && max_cluster <= 8 && cluster_cnt[0] == max_cluster)
+       if (clusters <= 1 && max_cluster <= 8 && cluster_cnt[0] == max_cluster) {
+#ifdef CONFIG_HOTPLUG_CPU
+               /* Don't use APIC shortcuts in CPU hotplug to avoid races */
+               genapic = &apic_physflat;
+#else
                genapic = &apic_flat;
-       else
+#endif
+       } else
                genapic = &apic_cluster;
 
 print: